Field of the Invention
The present invention relates to a safety device for aircraft that is used for explosion protection of a fuel tank.
Description of the Related Art
To achieve explosion protection of a main wing, serving as a fuel tank storing aviation fuel, the inside of the main wing is filled with nitrogen gas (Japanese Patent Laid-Open No. 2014-94662), or a lightning protection fastener provided with an insulating cap (Japanese Patent Laid-Open No. 2012-206662) is used in the main wing.
Inside a main wing, a ventilation passage that communicates with outside air is provided. Ventilation performed through the ventilation passage balances outside air pressure and pressure inside the main wing.
In the ventilation passage and around a vent hole facing the outside air, there is flammable gas that is a mixture of vaporized fuel steam and air. If the flammable gas is ignited at the time of a lightning strike or in the event of a fire in an airport, it is required to prevent a flame from entering the fuel tank through the ventilation passage.
In addition, if a flame is held in the vent hole, it is also required to prevent fuel in the fuel tank from being heated by heat transmitted from the flame through a skin of the main wing to be ignited in the fuel tank.
It is an object of the present invention to provide a safety device for aircraft, capable of reliably preventing an explosion of a fuel tank even if flammable gas is ignited.